Bacterial overgrowth is a condition found primarily in the elderly. It causes great discomfort and clinically important nutritional deficiencies. An underlying cause is decreased acid production, which occurs in at least 33% of people over 65 years. Management of overgrowth is hampered because low cost and easy to use diagnostic tests do not exist. Detection is meaningful because while the condition is never cured it can be controlled through antibiotics. Our objective is to develop an easy to use and cost effective test to detect bacterial overgrowth. Clinical utility is the ability to detect the bacteria as accurately as the gold standard (jejunal cultures) in patients exhibiting classic disease symptoms but whom ordinarily wouldn't receive expensive and invasive jejunal culture. The test is expected to accurately detect the condition pre and post therapy and lead to quality of life improvement. The novelty is that it is a non-invasive breath test that uses a naturally occurring sugar labeled with carbon-13 as a probe. If overgrowth is present, the labeled substrate will be metabolized by the bacteria in the small intestine and high concentrations of 13CO2 expired in the breath. PROPOSED COMMERCIAL APPLICATIONS: There are 25 million Americans over the age of 65 and they accounted for 10 million physician office visits with complaints of classic overgrowth symptoms. The proposed test will significantly reduce national health care expenditures because properly diagnosed cases will be lead to fewer office visits, more prudent use of antibiotics and better general health and well being in the elderly.